Arianespace successfully launches Sentinel-1D satellite marking key milestone for Ariane 6 program

Arianespace, Europe’s leading launch service provider, successfully launched the Sentinel-1D Earth observation satellite on November 4, 2025, at 21:02 UTC. The flight, which marked the third launch of the Ariane 6 rocket, lifted off from the Centre Spatial Guyanais in Kourou, French Guiana. This launch was a significant milestone for the Ariane 6 program, being only the fourth mission completed with this new rocket variant.

The latest launch used the Ariane 62 model, which is equipped with two solid rocket boosters from Avio known as the P120C. During the mission, the rocket followed a northward trajectory to place Sentinel-1D into a Sun-synchronous orbit, completing its journey in just under 34 minutes from liftoff to the successful separation of the satellite.

Standing at 54 meters, the Ariane 6 rocket used a combination of liquid hydrogen and liquid oxygen as propellants, including the Vulcain 2.1 engine for the main stage and a restartable Vinci engine for the upper stage. This mission implemented the shorter payload fairing, measuring 14 meters in height, suitable for the dimensions of the 2,184 kg Sentinel-1D satellite manufactured by Thales Alenia Space.

Liftoff was initiated with the main engine igniting seven seconds prior to the solid rocket boosters. After approximately 2 minutes and 14 seconds into the flight, the boosters detached, followed by the separation of the payload fairing within the next minute. The Ariane 6’s core stage continued to operate until around 7 minutes and 43 seconds post-launch, at which point the upper stage separated. Shortly thereafter, the Vinci engine began its operation, ensuring that Sentinel-1D was released at approximately 33 minutes and 51 seconds into the mission.

Following the successful deployment of the Sentinel-1D satellite, the upper stage was programmed for a deorbit burn to prevent it from becoming space debris. Currently, the Ariane 6 is not designed for reusability, but Arianespace is exploring methods to incorporate reusable technologies in future missions.

The Sentinel-1D satellite joins its sister satellite, Sentinel-1C, which was launched aboard a Vega-C rocket in December 2024, and the original Sentinel-1A, launched in 2014. These satellites are integral to Earth observation efforts, equipped with synthetic aperture radar (SAR) capabilities. The Sentinel series is part of a broader family of six Sentinel missions, which each use different observational techniques to monitor various aspects of the planet.

The European Space Agency (ESA) operates the Sentinel satellites as part of the Copernicus Programme, an initiative by the European Union that seeks to provide comprehensive data on the Earth’s environment. This program was established in 2014 and serves as a means of enhancing monitoring of changes in the Earth’s atmosphere, oceans, and land across numerous applications.

Sentinel-1D and its companion satellite, Sentinel-1C, are equipped with C-band SAR technology that facilitates observations under any weather conditions and even during nighttime. These satellites are set to provide continuous radar coverage of the Earth with a six-day revisit cycle, ensuring data consistency and reliability.

As Earth observation data continues to be critical for monitoring climate change, environmental degradation, and various terrestrial phenomena, the operational capacity of the Sentinel-1 series is essential. The forthcoming Sentinel satellites, including those numbered from Sentinel-7 to Sentinel-12, are expected to further enhance monitoring of human impacts on the environment and gather crucial data for scientific and policy-making efforts.

The next planned launch in the Ariane 6 timeline is set for December 2025, featuring two Galileo navigation satellites. Meanwhile, the next arrival in the Sentinel lineup, Sentinel-6B, is anticipated to launch no earlier than November 16, alongside the continued plans for the more powerful Ariane 64 variant arriving in 2026.